Comparative Genomics Across Modern Bird Species Reveal Insights into Pan- avian Genome evolution and Trait Biodiversity

Genomic comparison across multiple species is a key tool for revealing macroevolutionary patterns of gene and genome evolution. Using the full genomes of 48 avian species representing all major extant clades, we present the first large scale analysis of vertebrate genome evolution outside of mammals. We found the smaller size of avian genomes was largely the result of massive erosion of repetitive elements, large segmental deletions, as well as gene loss following the split from other reptiles. Avian genomes show a remarkably high degree of evolutionary stasis from chromosomes, gene synteny, down to single nucleotides. The overall of nucleotide substitution rate in birds is slower than in mammals, and varies among avian lineages according to life history and ecological factors. We also identified many protein-coding genes that are evolving non-neutrally, as well as non-coding RNA and regulatory regions that are highly conserved. Together our analyses reveal that genomic biodiversity across birds covaries with diverse adaptations to different lifestyles.